Archaeal transcription shares close homology with eukaryotic Pol II transcription but involves many fewer molecular components. Archaeal transcription systems therefore offer much simpler model approaches to probing the mechanics of Pol II transcription and investigating the aberrant transcription often associated with genetic diseases and cancers. Euryarchaea also contain archaeal histones that package their DMA into archaeal nucleosomes which have the same basic structure, DMA wrapping and compaction properties as the (H3/H4)2 histone tetramer at the center of the eukaryotic nucleosome. Archaeal transcription systems can therefore also directly address regulation imposed by histones and chromatin. To date, only archaeal transcription initiation has been studied in detail. Very little is known about archaeal transcription elongation, and archaeal transcription termination has not been established in vitro. The experiments proposed will establish an archaeal in vitro transcription system that exhibits transcription termination, and will identify the molecular signals/proteins that direct termination in Archaea. I will also determine how an archaeal RNA polymerase transcribes through an archaeal nucleosome template and determine the fate of the nucleosome.